1. Field of the Invention
The invention is directed to an improved fuel injection system for internal combustion engines, including a pressure booster between the fuel injector and a high pressure fuel source.
2. Description of the Prior Art
From German Patent Disclosure DE 43 11 627, fuel injection systems are already known in which an integrated pressure booster piston, by means of filling or evacuating a return chamber, makes it possible to increase the fuel injection pressure above the value furnished by a common rail system.
From U.S. Pat. No. 6,113,000, an injection system is known that has a high-pressure reservoir and a medium-pressure reservoir; the high-pressure reservoir can selectively also be filled with fuel.
German Patent Disclosure DE 199 10 970 describes fuel injection systems with pressure boosters, in which the injector and the pressure booster are each assigned a separate control valve.
German Patent Disclosure DE 43 11 627 also describes an injection system which requires not only a control valve but also an additional four-position slide valve.